Coolant circuit for vehicle and method for controlling such a circuit

ABSTRACT

Disclosed is a method for controlling a thermal regulation circuit of a vehicle, the circuit comprising first (2) and second (4) heat exchangers situated in series in a circulation direction of an air flow intended to pass through them in this order, the circuit further comprising an additional heat exchanger (16) situated upstream from the first heat exchanger (2) in the circulation direction of the air flow, the circuit being configured to allow the circulation of a refrigerant fluid in the first exchanger (2) and the circulation of a heat transfer fluid in the second exchanger (4) and in the additional exchanger (16), the method comprising a step of generating or increasing a flow rate of the heat transfer fluid in the additional exchanger (16) depending on operating modes of the circuit.

The field of the present invention is that of refrigerant circuits forvehicles, in particular for motor vehicles. The invention also relatesto a method for controlling such a circuit.

Motor vehicles are currently equipped with a refrigerant circuit used toheat or cool various zones or various components of the vehicle. It isparticularly known practice for this refrigerant circuit to be used tothermally treat an air flow sent into the interior of the vehicle.

In another application of this circuit, it is known practice to cool anelectrical storage device used to supply energy to the components of anelectric powertrain of the vehicle, particularly an electric motor,capable of causing said vehicle to move, and an associated electricconverter, intended to convert the DC electrical current delivered bythe electrical storage device into AC current for powering the electricmotor. The refrigerant circuit thus provides the energy capable ofcooling the electrical storage device when it is used during drivingphases. The refrigerant circuit is thus designed to cool this electricalstorage device for temperatures that remain moderate.

It is also known practice for the electrical storage device of thevehicle to be charged by connecting it for several hours to the domesticgrid. This long charging technique allows the temperature of theelectrical storage device to be kept below a certain threshold, whichallows any system for cooling the electrical storage device to bedispensed with.

A rapid charging technique may also be employed. It involves chargingthe electrical storage device at a high voltage and amperage, so as tocharge the electrical storage device over a short time of a few minutes.This rapid charging causes heating of the electrical storage device,which needs to be cooled. This heating governs the rating of thecomponents because this is one of the situations that are the mostsevere in terms of the cooling power that has to be supplied. Forexample it involves having to be able to dissipate more than 17 kW evenwhen the ambient air temperature might be high, for example 40° C.

Another factor in the rating of the device for conditions that are amongthe most severe in terms of the cooling power that has to be supplied isoperation with a dissipated power equal, or close, to the maximumavailable power. This corresponds to conditions in which the ambient airtemperature is high, namely 45° C., and the speed of the air flowavailable for cooling is 3 m/s. The temperature of a liquid coolant usedfor cooling the components of the electric powertrain of the vehicle isthen required to be below a maximum permissible temperature Tmax (forexample 70° C.) after the cooling of the electric converter.

In order to dissipate the heat that needs to be removed, each of thecircuits comprises an exchanger intended for an exchange of heat betweenan external air flow and, respectively, the refrigerant fluid and theliquid coolant. In order to optimize thermal efficiency, the ideal wouldbe for each exchanger to be able to have passing through it an ambientair flow, namely an air flow that has not already passed through anotherexchanger, the purpose of this being to avoid the temperature of the airflow passing through the exchanger then situated further downstreambeing higher than the ambient temperature as a result of having beenheated by the exchanger upstream of it.

That said, in a vehicle, these exchangers, which incidentally are knownas front-end exchangers, are generally positioned at the front of thevehicle, behind the radiator grille, and the surface area available islimited. It is therefore necessary to position the exchangers one behindanother in the direction of circulation of the air flow, and only one ofthem, situated furthest upstream, will be able to benefit from theambient air, the air flow passing through the one situated furtherdownstream then being at a temperature higher than the temperature ofthe ambient air.

A first option is therefore to prioritize the cooling of theliquid-coolant circuit by positioning the associated front-end exchangerforemost, namely upstream according to the direction in which the airflow circulates. The cooling of the refrigerant fluid is then limited,and the components of that circuit, particularly the compressor thereof,then need to be oversized, in order to have the necessary cooling poweravailable to them.

Another option is to prioritize the cooling of the refrigerant-fluidcircuit by positioning the associated front-end exchanger foremost,namely upstream according to the direction in which the air flowcirculates. That said, it is then the cooling of the heat-transfer fluidthat is limited.

An alternative solution, corresponding to an unpublished patentapplication in the name of the applicant company, has been envisioned.This consists in sharing the foremost position between two exchangers,namely an exchanger associated with the refrigerant-fluid circuit and anexchanger associated with the liquid-coolant circuit, and in assigningsecond place to an exchanger dedicated to the refrigerant fluid.Although it affords a significant improvement, this solution can beimproved still further.

The invention seeks to at least partially alleviate the aforementionedproblems and to this end proposes, in a first aspect, a circuit for thethermal regulation of a vehicle, said circuit comprising a first and asecond heat exchanger which are situated in series in a direction inwhich an air flow intended to pass through them in this ordercirculates, said circuit comprising a third heat exchanger through whichan ambient air flow is intended to pass, said circuit being configuredto allow a refrigerant fluid to circulate in series through the firstand third exchangers and a heat-transfer fluid to circulate through thesecond exchanger.

What is meant by an “ambient air flow” is an air flow which has passedneither through the first exchanger nor through the second exchangerbefore passing through the third exchanger. In other words, the air flowconcerned is at ambient temperature, namely at the temperature of theair outside the vehicle, when it passes through the third exchanger,because it has not been heated by another exchanger beforehand.

In that way, the invention provides a high level of heat dissipatingpower in relation to the refrigerant-fluid circuit, being able inparticular to provide one or more operating points corresponding tosevere conditions of use, such as the rapid charging of an energystorage device, and doing so by virtue of the third heat exchanger whichsupplements the dissipation power of the first exchanger, and doing soall the more effectively given that the third exchanger is intended toexchange heat with ambient air. At the same time, the heat-dissipationcapabilities of the heat-transfer fluid circuit are maintained by virtueof the second exchanger which is able to have an increased frontalsurface area in comparison with a situation in which it shares theavailable frontal surface area with another exchanger.

The circuit according to the invention can also comprise the followingfeatures, taken individually or according to any technically possiblecombination forming as many embodiments of the invention:

-   -   said circuit is configured so that the circulation of the        heat-transfer fluid allows a cooling of one or more components        of an electric powertrain of the vehicle,    -   said circuit is configured so that the series circulation of the        refrigerant fluid through the first and third exchangers provide        so-called rapid cooling of an electrical energy storage device        and/or thermal treatment of an interior of the vehicle.    -   said first and second heat exchangers are intended to be        positioned on the front face of the vehicle,    -   said first and second heat exchangers have substantially        identical frontal surface areas,    -   said third exchanger has a frontal surface area smaller than        that of the first and/or second exchangers,    -   said third exchanger is intended to be positioned on the front        face of the vehicle, upstream of the first and second exchangers        according to the direction of circulation of the air flow        passing through them,    -   said circuit comprises a fourth exchanger, configured to have        the heat-transfer fluid passing through it,    -   said circuit is configured to also selectively allow the        heat-transfer fluid to circulate through the second exchanger        and the heat-transfer fluid to circulate through the second and        the fourth heat exchanger,    -   the circulation of the heat-transfer fluid through the second        heat exchanger and through the fourth heat exchanger is in        series,    -   the third exchanger and the fourth exchanger are positioned        side-by-side in the direction of circulation of the air flow,    -   said third exchanger and said fourth exchanger, considered        together, have a frontal surface area substantially identical to        the frontal surface area of said first and/or of said second        heat exchanger,    -   said circuit comprises at least one valve for directing the        heat-transfer fluid downstream of the second exchanger        selectively, according to the direction of circulation of said        heat-transfer fluid, toward said fourth exchanger or toward the        component or components of the electric powertrain of the        vehicle,    -   said circuit is configured to selectively allow the refrigerant        fluid to circulate through the first exchanger, or the        refrigerant fluid to circulate in series through the first and        third exchangers,    -   said circuit is configured so that circulation of the        refrigerant fluid through the first heat exchanger provides        so-called operational cooling of the electrical storage device        and/or thermal treatment of an interior of the vehicle,    -   said circuit comprises a fifth exchanger, referred to as a        bi-fluid heat exchanger, configured to allow an exchange of heat        between said refrigerant fluid and said heat-transfer fluid,    -   said circuit comprises a heating radiator intended to have the        heat-transfer fluid passing through it, said circuit being        configured so that the heat-transfer fluid circulating through        the bi-fluid exchanger circulates through said radiator, in at        least one mode of operation of said circuit,    -   said circuit is configured so that, in at least one mode of        operation, said fifth exchanger is situated upstream of said        first exchanger in the direction of circulation of the        refrigerant fluid,    -   said circuit comprises a bottle configured for separating the        vapor phase and the liquid phase of said refrigerant fluid,    -   said bottle is incorporated into said first exchanger,    -   said bottle is situated between said first and said third        exchanger, in the direction of circulation of the refrigerant        fluid.

In another aspect of the invention, the applicant has noted that, giventhe different times at which the rapid charging of the battery and theconditions of operation at maximum power occur, there is anotherapproach that can be taken for optimizing the dissipation of heat.

Thus, according to another aspect of the invention, the inventionrelates to a method for controlling a circuit for the thermal regulationof a vehicle, said circuit comprising a first and a second heatexchanger which are situated in series in a direction in which an airflow intended to pass through them in this order circulates, saidcircuit further comprising an additional heat exchanger situatedupstream of the first heat exchanger according to the direction ofcirculation of the air flow, said circuit being configured to allow arefrigerant fluid to circulate through the first exchanger and aheat-transfer fluid to circulate through the second exchanger andthrough the additional exchanger, said method comprising a step in whicha flow of the heat-transfer fluid in the additional exchanger isgenerated or increased according to the mode of operation of thecircuit.

In other words, according to this aspect of the invention, the heatexchanger that is situated foremost, namely the additional heatexchanger, does not always have the heat-transfer fluid passing throughit. It therefore does not heat the incident air flow. It is thereforepossible to maintain a good heat-dissipation capability for therefrigerant fluid when the additional heat exchanger does not have theheat-transfer fluid passing through it, for example when the vehicle isstationary and the vehicle electrical storage device needs to be cooled.Conversely, when the additional heat exchanger does have theheat-transfer fluid passing through it, the dissipation power affordedby the heat-transfer fluid is optimized and allows the cooling of thevehicle powertrain, even under the most severe conditions such asoperation at maximum power.

The method according to the invention can also comprise the followingfeatures, taken individually or according to any technically possiblecombination forming as many embodiments of the invention:

-   -   said circuit is configured in such a way that the air flow        passing through said additional heat exchanger is an ambient air        flow,    -   said method comprises a step of controlling at least one        parameter relating to the heat-transfer fluid,    -   said parameter is the temperature of the heat-transfer fluid,    -   the step in which the flow of the heat-transfer fluid in the        additional exchanger is generated or increased is performed        according to a value of said parameter,    -   the step in which the flow of the heat-transfer fluid in the        additional exchanger is generated or increased is performed by        comparing the value of the parameter against a threshold value,    -   said circuit is configured so that the circulation of the        heat-transfer fluid allows a cooling of one or more components        of an electric powertrain of the vehicle,    -   said circuit is configured so that the circulation of the        heat-transfer fluid allows a cooling of an electric converter        intended to convert a DC electric current delivered by an        electrical storage device into an AC current for powering an        electric motor capable of causing said vehicle to move,    -   the step in which the flow of the heat-transfer fluid in the        additional exchanger is generated or increased occurs if the        temperature of the heat-transfer fluid is slightly below, equal        to or greater than the maximum permissible temperature Tmax,    -   said method comprises a step of selectively allowing a        circulation of the heat-transfer fluid through the second        exchanger and a circulation of the heat-transfer fluid through        the second exchanger and through the additional heat exchanger,    -   said circuit comprises at least one valve for directing the        heat-transfer fluid downstream of the second exchanger        selectively, according to the direction of circulation of said        heat-transfer fluid, toward said additional heat exchanger or        toward the component or components of the electric powertrain of        the vehicle,    -   said step in which the flow of the heat-transfer fluid in the        additional exchanger is generated or increased comprises a step        of opening/closing said valve, in an all-or-nothing mode and/or        partially,    -   said valve is formed by a thermostat and/or by an electronically        controlled valve,    -   the circulation of the heat-transfer fluid through the second        heat exchanger and through the additional heat exchanger is in        series,    -   said first and second heat exchangers have substantially        identical frontal surface areas,    -   said additional exchanger has a frontal surface area smaller        than or equal to that of the first and/or second exchangers,    -   said first and second heat exchangers as well as said additional        exchanger are intended to be positioned on the front face of the        vehicle,    -   the cooling fluid is cooled in the following sub-steps:        -   a sub-step (a) wherein said air flow is generated and/or            accelerated using a motor-fan unit, and/or a sub-step (b)            wherein a cross section for the passage of said air flow is            increased by opening one or more mobile flaps or shutters            intended to limit a flow rate of said air flow,        -   a sub-step (c) wherein the flow of the heat-transfer fluid            through said additional heat exchanger is generated and/or            increased.    -   the order of said sub-steps is modified according to the speed        of the vehicle,    -   when the vehicle speed is above a threshold speed, there is an        envisioned initial situation in which the flaps or shutters are        closed so that the cross section for the passage of said air        flow is nil or minimal    -   when the vehicle speed is above the threshold speed,        sub-step (c) is performed first of all, followed by sub-step (b)        if that is still not enough to achieve a required setpoint    -   when the vehicle is stationary and/or when the vehicle speed is        below the threshold speed, sub-step (a) is performed first of        all, and then, if that is still not enough to achieve a required        setpoint, sub-step (c) is performed,    -   when the vehicle is stationary and/or when the vehicle speed is        below the threshold speed, sub-step (b) is performed if the        setpoint has not been achieved at the end of sub-step (a), and        then sub-step (c) is performed, if the setpoint has not been        achieved at the end of sub-step (b),    -   the load on a refrigerant-fluid circulation loop is reduced if        the setpoint is not achieved despite implementation of sub-steps        (a), (b) and (c),    -   said threshold speed of the vehicle is adapted according to the        ambient temperature,    -   said circuit comprises an exchanger, known as a bi-fluid        exchanger, configured to allow an exchange of heat between said        refrigerant fluid and said heat-transfer fluid,    -   said circuit comprises a heating radiator intended to have the        heat-transfer fluid passing through it, said circuit being        configured so that the heat-transfer fluid circulating through        the bi-fluid exchanger circulates through said radiator, in at        least one mode of operation of said circuit,    -   said circuit is configured so that, in at least one mode of        operation, the bi-fluid exchanger is situated upstream of said        first exchanger in the direction of circulation of the        refrigerant fluid,    -   said circuit comprises a bottle configured for separating the        vapor phase and the liquid phase of said refrigerant fluid,    -   said bottle is incorporated into said first exchanger.

This aspect of the invention can be combined with the first aspect ofthe invention. Said circuit then comprises the third heat exchanger asdescribed above. In addition, the additional heat exchanger correspondsto the fourth exchanger of said first aspect of the invention.

The invention also relates to a heat exchange module comprising thefirst, the second as well as the third heat exchanger and/or the fourthexchanger, namely the additional heat exchanger of the circuit describedabove. Advantageously, said module further comprises the valve thatallows the selective directing of the heat-transfer fluid downstream ofthe second exchanger.

Further features and advantages of the invention will become apparentfrom reading the following detailed description, for an understanding ofwhich reference is made to the appended drawings, in which:

FIG. 1 schematically illustrates one exemplary embodiment of a firstcircuit according to the invention comprising a loop for the circulationof a refrigerant fluid and a loop for the circulation of a heat-transferfluid,

FIG. 2 schematically illustrates the circulation of the various fluidsaccording to a first mode of operation of the circuit of FIG. 1

FIG. 3 schematically illustrates the circulation of the various fluidsaccording to a second mode of operation of the circuit of FIG. 1

FIG. 4 schematically illustrates the circulation of the various fluidsaccording to a third mode of operation of the circuit of FIG. 1

FIG. 5 is a flow diagram illustrating one exemplary embodiment of acontrol method according to the invention.

As illustrated in FIGS. 1 to 4, the invention relates to a thermalregulation circuit for a vehicle, particularly a motor vehicle. Itcomprises in this instance a loop, particularly a closed loop, for thecirculation of a refrigerant fluid and a loop, particularly a closedloop, for heat-transfer fluid.

The terms upstream and downstream used in the following descriptionrefer to the direction of circulation of the fluid in question, that isto say the refrigerant fluid, the heat-transfer fluid, a flow of airexternal to an interior of the vehicle and/or an interior air flow sentto the interior of the vehicle.

In FIG. 1, the refrigerant-fluid loop is illustrated in solid line andthe heat-transfer fluid loop is illustrated in chain line. In FIGS. 2 to4, for each of the loops, the portions through which their respectivefluid is passing are shown in solid line and the portions withoutcirculating fluid are shown in dotted line. Moreover, the circulation ofthe refrigerant fluid is illustrated with its direction of circulationindicated by arrows. Use is also made of solid line of different linethicknesses. More specifically, the thickest lines correspond tohigh-pressure portions, the intermediate-thickness lines correspond tointermediate portions and the thinnest lines correspond to low-pressureportions of the refrigerant-fluid loop.

The identifiers “first”, “second”, etc. used hereinafter are notintended to indicate a level of hierarchy of or to order the terms theyaccompany. These identifiers serve to distinguish the terms which theyaccompany and can be interchanged without narrowing the scope of theinvention.

The refrigerant fluid is, for example, a fluid capable of transitioningfrom a liquid phase to a gas phase and vice versa under the temperatureand pressure conditions of the circuit. It may be a fluid known by thename of R134a or a fluid known by the name of R1234yf. It may even be afluid that remains essentially in the gaseous state, such as R744.

The heat-transfer fluid is, for example, a liquid, notably water withthe addition of an antifreeze such as glycol.

Said circuit comprises a first heat exchanger 2, a second heat exchanger4 and a third heat exchanger 6. Said circuit is configured to allow therefrigerant fluid to circulate in series through the first and thirdexchangers 2 and 6, and the heat-transfer fluid to circulate through thesecond exchanger 4. In other words, in this instance, the first andthird exchangers are in the refrigerant-fluid circulation loop and thesecond exchanger 4 is in the heat-transfer fluid loop.

Furthermore, the first exchanger 2 and the third exchanger 6 aresituated in series in a direction of circulation of an air flow,illustrated by an arrow identified F1, which flow is intended to passthrough them in that order. For its part, the third heat exchanger 6 isintended to have passing through it an ambient air flow, in other wordsair that has not yet been heated by the first and/or the secondexchangers 2 and/or 4. As will be detailed later on, in the embodimentillustrated, this is the same air flow F1 as passes through the firstand second exchangers 2, 4, the air flow F1 therefore passing, in thisorder, through the third exchanger 6, the first exchanger 2 and thesecond exchanger 4.

By placing the first and third heat exchangers 2 and 6 in series withrespect to the refrigerant fluid, a high heat-dissipation power isobtained, especially when the third exchanger 6 has fresh air passingthrough it and therefore cools the refrigerant fluid all the moreeffectively. The latter fluid can thus be used to cool variouscomponents or regions of the vehicle, even under the most severeconditions of use of the circuit. Furthermore, the second exchanger 4can be used for cooling other components using the heat-transfer fluid,this being with the possibility of exhibiting a large frontal surfacearea because it is situated downstream of the first exchanger 2 in thedirection of circulation of the air flow. This frontal surface areatherefore does not interfere with that of the third exchanger 6 which ispositioned either upstream of the first exchanger 2 in the direction ofcirculation of the air flow or elsewhere in the vehicle provided that itcan have an ambient air flow passing through it.

As will be expanded upon later on, the circuit may be configured so thatthe passage of the refrigerant fluid in series through the first andthird exchangers 2 and 6 does not occur systematically but only incertain modes of operation. Such is the case in the example illustrated,in which series circulation occurs in the modes of operation of FIGS. 2and 4 but not in the mode of operation of FIG. 3.

The first exchanger 2 is formed for example of a gas cooler orcondenser. The third exchanger 6 is configured, for example, to performsupercooling of said refrigerant fluid after it has passed through thegas cooler or condenser. These may, for example, the exchangerscomprising a heat exchange core bundle of tubes and fins. The tubes areintended for the circulation of the refrigerant fluid. The fins are incontact with the tubes and are intended to have the air flow passthrough them. Said condenser has one or more passes for the circulationof the refrigerant fluid.

Said circuit is configured here so that the circulation of theheat-transfer fluid can be used, for example, to cool one or morecomponents of an electric powertrain of the vehicle, such as an electricmotor 8, capable of causing said vehicle to move, and an associatedelectric converter 10, intended to convert the DC electrical currentdelivered by an electrical storage device into AC current for poweringthe electric motor 8. To do that, the heat-transfer fluid circulationloop advantageously comprises a first leg 12 passing in this orderaccording to the direction of circulation of the heat-transfer fluidthrough the electric converter 10 and the electric motor 8. As analternative, the converter 10 and/or the motor 8 do not have theheat-transfer fluid passing through them directly, but are passedthrough by an auxiliary fluid, said auxiliary fluid exchanging heat withthe heat-transfer fluid by means of a heat exchanger connected to thecomponent concerned by a specific auxiliary-fluid circulation loop.

In the embodiment illustrated, such cooling occurs in the mode ofoperation illustrated in FIG. 2.

Said circuit is furthermore in this instance configured so thatcirculation in series of the refrigerant fluid through the first andthird exchangers 2 and 6 provides so-called rapid cooling of theelectrical energy storage device and/or thermal treatment of an interiorof the vehicle. The electrical energy storage device is not depicted assuch. It may be in direct contact with a component of therefrigerant-fluid circulation loop such as a cooler 14. As analternative, it may be cooled by an auxiliary fluid, itself exchangingheat with the refrigerant fluid, for example by means of said cooler 14.In the embodiment illustrated, the associated mode of operation,referred to as rapid cooling of the electrical energy storage device, isencountered, FIG. 4.

As a preference, said first and second heat exchangers 2, 4 are intendedto be positioned on the front face of the vehicle, for example behindthe radiator grille thereof. They advantageously have substantiallyidentical frontal surface areas, particularly so that each can occupythe largest available area. What is meant by frontal surface area is thesurface area of the exchanger in a plane perpendicular to the air flowF1, namely in a plane substantially parallel to the radiator grille.

Advantageously, as already mentioned, said third exchanger 6 is alsointended to be positioned on the front face of the vehicle and have theair flow F1 passing through it. It is therefore situated upstream of thefirst and second exchangers 2 and 4, in the direction of circulation ofthe air flow.

With such a location, said third exchanger 6 has a frontal surface areasmaller than that of the first and/or second exchangers 2, 4. That said,this feature could also apply when the third exchanger 6 is sited atanother location. In this regard, said third exchanger 6 may besituated, for example, in a wheel arch. Its frontal surface area is thentailored to the space available.

Advantageously, said circuit comprises a fourth exchanger 16 which inthis instance is positioned next to the third exchanger 6 so that thethird and fourth exchangers 6 and 16 have said air flow F1 passingthrough them in parallel. As a preference, said third exchanger 6 andsaid fourth exchanger 16, considered together, have a frontal surfacearea substantially identical to the frontal surface area of said firstand second heat exchangers 2 and 4.

The second exchanger 4 is formed, for example, of a cooling radiator. Itmay be qualified as a low-temperature radiator. The fourth exchanger 16is configured, for example, to perform additional cooling of saidheat-transfer fluid. It may be qualified as a very-low-temperatureexchanger. These may, for example, be exchangers comprising a heatexchange core bundle of tubes and fins. The tubes are intended for thecirculation of the cooling fluid. The fins are in contact with the tubesand are intended to have the air flow pass through them.

Said circuit is configured to also selectively allow the heat-transferfluid to circulate through the second exchanger 4, without passingthrough the fourth exchanger 16, as is the case in FIG. 4, and theheat-transfer fluid to circulate through the second and the fourth heatexchangers 4 and 16, as is the case in FIGS. 2 and 3. In other words, inthis instance, said fourth exchanger 16 is incorporated into theheat-transfer fluid circulation loop. When there is no circulation ofheat-transfer fluid in the fourth exchanger 16, this promotes theeffectiveness of the first exchanger 2 because the air flow passingthrough the latter is then an air flow at ambient temperature, at leastover that portion of said first exchanger 2 that lies facing the fourthexchanger 16. When the heat-transfer fluid is circulating both throughthe second exchanger 4 and the fourth exchanger 16, this promotesgreater capacity for the heat-transfer fluid circulation loop todissipate heat at the front face, especially when the fourth exchanger16 has passing through it a flow of ambient air, as in the embodimentillustrated.

The circulation of the heat-transfer fluid through the second heatexchanger 4 and through the fourth heat exchanger 16 is, in thisinstance, in series. As an alternative, it is in parallel.

Said circuit further comprises at least one valve 18 for directing theheat-transfer fluid downstream of the second exchanger 4 selectively,according to the direction of circulation of said heat-transfer fluid,toward said fourth exchanger 16, as in FIGS. 2 and 3, or directly towardthe rest of the circuit, as in FIG. 4. This is, for example, a three-wayvalve, in this instance having a first inlet, a second inlet, and acommon outlet.

Said first inlet is connected, for example, to a portion 20 of a secondleg 22 of the coolant-fluid circulation loop comprising said secondexchanger 4, said portion 20 allowing said fourth exchanger 16 to bebypassed after exiting the second exchanger 4. Said second inlet isconnected to the fourth heat exchanger 16. Said common outlet isconnected in particular to the first leg 12 of said cooling-fluidcirculation loop.

As an alternative, said valve 18 comprises a common inlet, a firstoutlet and a second outlet. The inlet is then connected to the secondexchanger 4, the first outlet to the portion 20 of the second leg 22 ofthe cooling-fluid circulation loop, and the second outlet to the fourthheat exchanger 16.

Said valve 18 is notably formed of a thermostat and/or of anelectronically controlled valve allowing communication to be establishedselectively between the first and/or the second inlet of said valve andthe common outlet and/or between the common inlet and the first and/orthe second outlet.

As mentioned above, as a preference, said circuit is configured to allowthe refrigerant fluid to circulate selectively through the firstexchanger 2 without passing through the third exchanger 6, as in FIG. 3,or the refrigerant fluid to circulate in series through the first andthird exchangers 2 and 6, as in FIGS. 2 and 4. In that way, it ispossible for the third exchanger 6 not to be used systematically, thispotentially being advantageous for limiting the pressure drops in therefrigerant-fluid loop when the need to dissipate heat is limited.

Such a mode of operation is for example employed for so-calledoperational cooling of the electrical storage device, which is to saycooling that requires less dissipation of heat than is required in thecase of rapid recharging, and/or for a thermal treatment of the interiorof the vehicle. Such is, for example, the case for operation inheat-pump mode, as in FIG. 3. In such an embodiment, according to theembodiment illustrated, heat energy is taken from the air flow F1passing through the first exchanger 2 and restored, as will be expandedupon later, to an air flow illustrated as F2 that is intended to enterthe vehicle interior in order to heat same. Said circuit is thusconfigured so that the circulation of the refrigerant fluid through thefirst heat exchanger 2 without passing through the third exchanger 6allows such a result to be achieved.

As a preference, said circuit comprises a fifth exchanger 24, known as abi-fluid exchanger, configured to allow an exchange of heat between saidrefrigerant fluid in said heat-transfer fluid. Such an exchanger istherefore positioned both in the refrigerant-fluid loop and thecooling-fluid loop. This is, for example, a condenser, notably acondenser of the stacked plates type.

As a preference, said circuit, particularly said heat-transfer fluidcirculation loop, comprises a heating radiator 26 through which theheat-transfer fluid is intended to pass. Said circuit is configured sothat the heat-transfer fluid circulating in the bi-fluid exchanger 24circulates through said heating radiator 26, according to at least onemode of operation of said circuit, notably the heat-pump mode mentionedabove.

In this mode, as illustrated in FIG. 3, the heat energy is taken fromthe air flow F1 passing through the first exchanger 2 and transmitted bysaid exchanger 2 to the refrigerant fluid. This energy is thereforetransmitted to the cooling fluid by said fifth exchanger 24 and to theair flow F2 intended to enter the vehicle interior by the heatingradiator 26.

As a preference, said circuit is configured so that, in at least onemode of operation, said fifth exchanger 24 is situated upstream of saidfirst exchanger 2 according to the direction of circulation of therefrigerant fluid. The modes of operation involved are, for example, anair conditioning mode encountered in FIG. 2 according to the embodimentillustrated, and/or the mode of rapid cooling of the electrical energystorage device (remember this is illustrated in FIG. 4). Thus, in themodes concerned, the refrigerant fluid experiences all of the following:a pre-cooling in the fifth exchanger 24, a cooling, possibly with changeof phase, in the first exchanger 2 and, if necessary, a supercooling inthe third exchanger 6. The change in enthalpy of the refrigerant fluidis therefore optimized, making it possible to limit the amount of powerthat has to be supplied to the refrigerant-fluid loop, for the sameperformance.

Said circuit may comprise a bottle, not illustrated, configured forseparating the vapor phase and the liquid phase of said refrigerantfluid. Said bottle is, for example, incorporated into said firstexchanger 2 which may, or may not, then comprise one or moresupercooling passes within its core bundle. This supercooling combineswith the cooling supplied by the third exchanger 6 in the modes ofoperation in which series circulation through the first and thirdexchangers 2 and 6 occurs. As an alternative, said bottle is situatedbetween said first and third exchangers 2 and 6, in the direction ofcirculation of the refrigerant fluid. Said bottle is advantageouslyfurnished with a filter and/or with a desiccant.

According to the embodiment illustrated, the cooling-fluid circulationloop comprises the first leg 8 and the second leg 22 already mentioned,as well as a third leg 28 and a fourth leg 30, all of said legs 12, 22,28, 30 running parallel with one another.

The first leg 12 comprises the electric converter 10 and the electricmotor 8. It further comprises a first pump 32 for circulating thecooling fluid.

The second leg 22 comprises the second exchanger 4 and the three-wayvalve 18. In parallel with its portion 20, it further comprises asub-leg 34 equipped with said fourth exchanger 16.

The third leg 28 comprises the bi-fluid exchanger 26 and a second pump36 for circulating the heat-transfer fluid.

The fourth leg 30 comprises a first two-way valve 38 and the heatingradiator 26. In this instance it further comprises an electrical heatingdevice 40 for heating the cooling fluid, and which is intended to beused in combination with the heating radiator 26, if need be.

Said cooling-fluid circulation loop may further comprise a secondtwo-way valve 42, situated between, on the one hand, the first andsecond legs 12 and 22 and, on the other hand, the third and fourth legs28 and 30 on the downstream side of the second pump 36.

Said circuit, particularly said refrigerant fluid circulation loop,comprises a compression device 50 allowing said refrigerant fluid to becirculated. It will be noted that the compression device 50 can take theform of an electric compressor, that is to say a compressor whichcomprises a compression mechanism, an electric motor and possibly acontroller.

Downstream of said compression device 50, said refrigerant-fluidcirculation loop comprises said bi-fluid exchanger 24, a third two-wayvalve 52, said first exchanger 2, said third exchanger 6, a non-returnvalve 54, a first pass 56 of an internal exchanger 58 and, in parallelwith one another in respective legs, an evaporator 58 and the cooler 14,and then an accumulator 60 and a second pass 62 of the internalexchanger 58. These components succeed one another in this order in asub-loop through which the refrigerant fluid returns to the compressiondevice 50 after having passed through the second pass 62 of the internalexchanger 58.

Said circuit further comprises a first, a second and a third bypass leg64, 66 and 80, for modifying the path of the refrigerant fluid.

The first bypass leg 64 is situated between a first point of divergence68 and a first point of convergence 70. The first point of divergence 68is situated between the third two-way valve 52 and the first exchanger2. The first point of convergence 70 is situated between the non-returnvalve 54 and the first pass 56 of the internal exchanger 58. Said firstbypass leg 64 comprises a first expansion member 76. Said expansionmember is configured to selectively completely open said first bypassleg 64, completely close said first bypass leg 64, or expand therefrigerant fluid circulating through said first bypass leg 64.

The second bypass leg 66 is situated between a second point ofdivergence 72 and a second point of convergence 74. The second point ofdivergence 72 is situated between the bi-fluid exchanger 24 and thethird two-way valve 52. The second point of convergence 74 is situatedbetween the first pass 56 of the internal exchanger 58 and a portion, inthis instance a point, of the above-mentioned sub-loop allowing theevaporator 58 and the cooler 14 to be supplied in parallel. Said secondbypass leg 66 comprises a fourth two-way valve 78.

The third bypass leg 80 is situated between a third point of divergence82 and a third point of convergence 84. The third point of divergence 82is situated between the first exchanger 2 and the third exchanger 6. Thethird point of convergence 84 is situated between, on the one hand, aportion, in this instance a point, of the above-mentioned sub-loopallowing the refrigerant fluid leaving the evaporator 58 and leaving thecooler 14 to be collected in parallel and, on the other hand, theaccumulator 60. Said third bypass leg 80 comprises a fifth two-way valve86.

The refrigerant-fluid circulation loop further comprises a second and athird expansion member 88 and 90, these respectively being situatedupstream of the evaporator 58 and of the cooler 14 in the associatedlegs. Said expansion members are configured to selectively completelyopen said legs, completely close said legs, or expand the refrigerantfluid circulating through said legs.

According to the mode of operation illustrated in FIG. 2, the circuitprovides both an air conditioning mode and a mode in which the heatreleased by the component or components 8, 10 of the electric powertrainof the vehicle is dissipated in such a way as to cool the cooling fluidto below the maximum permissible temperature Tmax downstream of theconverter 10, even in conditions of use such as operation at maximumpower.

In this mode of operation, the cooling fluid circulates in the first leg12, the second leg 22, passing via the sub-leg 34, and in the third leg28, but does not circulate through the fourth leg 30. The three-wayvalve 18 is open so as to cause the cooling fluid to circulate throughthe fourth exchanger 16, as explained above. The first two-way valve 38is closed. The second two-way valve 42 is open. The first and/or secondpumps 32, 36 are active. Thus, the cooling fluid circulates in loopthrough the first and second legs 12, 22 so that the heat released bythe components of the powertrain 8, 10 is dissipated into the air by thesecond and fourth exchangers 4, 16. If the cooling requirements remainlimited, the cooling fluid may pass through the bypass portion 20 ratherthan through the sub-leg 34. The cooling fluid also circulates throughthe third leg 28, in parallel with the first leg 12, in order to allowcooling of the refrigerant fluid at the bi-fluid exchanger 24.

Still in this mode of operation, the refrigerant fluid follows thesub-loop mentioned above. The fourth two-way valve 52 is open and saidsecond and third expansion members 88 and 90 operate like an expansionvalve. The first expansion member 76 is closed as are the fourth two-wayvalve 78 and the fifth two-way valve 86. The dissipation of heatperformed by the bi-fluid exchanger 24 into the cooling fluid and by thefirst and third exchangers 2 and 6 into the air flow F1, allows, on theone hand, the cooling of the electrical energy storage device, using thecooler 14 and, on the other hand, the air conditioning of the vehicleinterior, using the evaporator 58 which cools the air flow F2, notablyin phases during which the vehicle is moving.

According to the mode of operation illustrated in FIG. 3, as alreadymentioned, the circuit provides a heat-pump mode, in this instancewithout cooling of the electrical storage device even though a heat-pumpmode remains compatible with operational cooling of said storage deviceusing the circuit illustrated.

In this mode of operation, the cooling fluid circulates in the first leg12, the second leg 22, passing via the sub-leg 34, and in the third leg28, and the fourth leg 30. The three-way valve 18 is open so as to causethe cooling fluid to circulate through the fourth exchanger 16, asexplained above. The first two-way valve 38 and the second two-way valve42 are open. The first and/or second pumps 32, 36 are active. Thus, thecooling fluid circulates in a loop in the third and the fourth leg 28and 30 so that the heat transmitted by the bi-fluid exchanger 24 isdissipated into the air flow F2 by the heating radiator 26 to warm thevehicle interior. Circulation through the first leg 12 is in parallelwith the circulation in the third leg 28, so as to recover the heatreleased by the components of the electric powertrain 8, 10. As analternative, the circulation of the cooling fluid through the second leg22 may be shut off, in this instance using said three-way valve 18.

Still in this mode of operation, the refrigerant fluid follows adifferent path than that of the sub-loop mentioned above. The thirdtwo-way valve 52 is closed as are said second and third expansionmembers 88 and 90. The first expansion member 76 operates as anexpansion valve. The fourth two-way valve 78 and the fifth two-way valve86 are open. Downstream of the compression device 50, the refrigerantfluid thus passes in succession through said bi-fluid exchanger 24, thefifth two-way valve 52, the first pass 56 of the internal exchanger 58,the first expansion member 76, said first exchanger 2, said sixth valve86 and then the accumulator 60 and a second pass 62 of the internalexchanger 58. The first exchanger 2 therefore operates as an evaporatorand collects heat from the air flow F1, which heat will be transmittedto the air flow F2 by the bi-fluid exchanger 24 and the heating radiator26.

According to the mode of operation illustrated in FIG. 4, as alreadymentioned, the circuit provides rapid cooling of the energy storagedevice. Such operation generally occurs when the vehicle is stationaryand the other cooling requirements or heating requirements are generallylow.

In this mode of operation, the cooling fluid circulates in the secondleg 22, passing via the portion 20, and in the third leg 28, butcirculates through neither the first leg 12 nor the fourth leg 30. Thethree-way valve 18 is open so as to cause the cooling fluid to circulatethrough the portion 20, as explained above. The first two-way valve 38is closed. The second two-way valve 42 is open. The first part 32 isinactive whereas the second pump 36 is active. In that way, the coolingfluid circulates in a loop through the second leg 12 and the third leg28 so as to provide a minimum flow of cooling fluid through the bi-fluidexchanger 24 so that said cooling fluid does not begin to boil under theeffect of the heat dissipated by the refrigerant fluid.

Still this mode of operation, the refrigerant fluid follows the samepath as in the case of FIG. 2, namely the sub-loop mentioned above. Thedissipation of heat performed by the bi-fluid exchanger 24 into thecooling fluid and by the first and the third exchangers 2 and 6 into theair flow F1 allows the rapid cooling of the energy storage device usingthe cooler 14.

Another aspect of the invention relates to a method for controlling acircuit for the thermal regulation of a vehicle. This may be the circuitdescribed provided that it comprises said fourth exchanger 16 which isthen qualified as an additional exchanger according to this aspect ofthe invention. That said, more broadly, said method may also apply toconfigurations without the third exchanger 6, the remainder of thecircuit then advantageously remaining the same.

In the event of the absence of said third exchanger 6, said additionalheat exchanger 16 preferably has a frontal surface area substantiallyequal to that of the first and/or second heat exchangers 2, 4.

According to this other aspect of the invention, said method comprises astep wherein a flow of heat-transfer fluid through the additionalexchanger 16 is generated or increased according to the mode ofoperation of the circuit. In that way, whether or not a third exchanger6 is available, this encourages the dissipation of heat by the coolingfluid by combining, where necessary, the second exchanger 4 and theadditional exchanger 16, as is the case for example in the mode ofoperation of FIG. 2, in the way already seen, this being all the moreeffective when said additional heat exchanger 16 has ambient air flowpassing through it.

More specifically, said method comprises a step of selectively allowinga circulation of the heat-transfer fluid through the second exchanger 4,without it passing through the additional exchanger 16, and acirculation of the heat-transfer fluid through the second exchanger 4and through the additional heat exchanger 16. The heat dissipation poweris thus modified according to the requirements.

As a preference, said method comprises a step of controlling at leastone parameter relating to the heat-transfer fluid. This in particular isthe temperature of the heat-transfer fluid.

The step in which the flow of the heat-transfer fluid in the additionalexchanger 16 is generated or increased is performed on the basis of avalue of said parameter, notably by comparing the value of the parameteragainst a threshold value.

By way of example, the step in which the flow of the heat-transfer fluidin the additional exchanger is generated or increased occurs if thetemperature of the heat-transfer fluid is slightly below, equal to orgreater than the maximum permissible temperature Tmax,

Said step in which the flow of the heat-transfer fluid in the additionalexchanger is generated or increased in this instance comprises a step ofopening/closing said three-way valve 18, in an all-or-nothing modeand/or partially.

As illustrated in FIG. 5, the cooling fluid is cooled in the followingsub-steps:

-   -   a sub-step (a) wherein said air flow is generated and/or        accelerated using a motor-fan unit, and/or a sub-step (b)        wherein a cross section for the passage of said air flow is        increased by opening one or more mobile flaps or shutters        intended to limit a flow rate of said air flow,    -   a sub-step (c) wherein the flow of the heat-transfer fluid        through said additional heat exchanger 16 is generated and/or        increased.

Advantageously, the order of said sub-steps may moreover be modifiedaccording to the speed of the vehicle, notably according to the speed ofthe vehicle with respect to a threshold speed.

In particular, when the vehicle speed is above the threshold speed,there is an envisioned initial situation in which the flaps or shuttersare closed so that the cross section for the passage of said air flow isnil or minimal.

When the vehicle speed is above the threshold speed, sub-step (c) isperformed first of all, followed by sub-step (b) if that is still notenough to achieve a required setpoint. On the other hand, sub-step (a)has very little effect.

Successively, information about the vehicle is acquired in a first step100. The flow rate and the temperature of the cooling fluid as well asthe speed and the temperature of the air flow F1 are measured in asecond step 102. Information on the refrigerant-fluid circulation loopis acquired in a third step 104 and then a test is performed to checkthat the temperature of the liquid coolant is above a setpoint, possiblyincorporating a measurement uncertainty, in a fourth step 106.

If the result of the fourth step 106 is negative, the monitoringcontinues, looping back to the first step 100.

If the result of the fourth step 106 is positive, then a test isperformed to check if a rotational speed of the motor-fan unit is amaximum speed, in a fifth step 108.

If the result of the fifth step 108 is negative, then the speed of themotor-fan unit is increased, this being done in a sixth step 110, andthe monitoring continues, looping back to the first step 100.

If the result of the fifth step 108 is positive, then a test isperformed to check whether the flaps or shutters are open to the maximumextent, in a seventh step 112.

If the result of the seventh step 112 is negative, then the extent towhich the flaps or shutters are open is increased, this being done in aneighth step 114, and the monitoring continues, looping back to the firststep 100.

If the result of the seventh step 112 is positive, then a test isperformed to check whether the flow rate through the additional heatexchanger 16 is at a maximum, in a ninth step 116.

If the result is negative, then the flow rate through the additionalheat exchanger 16 is increased, notably using the three-way valve 18mentioned above, this being done in one or more tenth steps 118, and themonitoring continues, looping back to the first step 100.

In other words, when the vehicle is stationary and/or when the vehiclespeed is below the threshold speed, sub-step (a) is performed first ofall, and then, if that is still not enough to achieve the requiredsetpoint, sub-step (b) is performed, and then, if that is still notenough to achieve the required setpoint, sub-step (c) is performed.

Using such a strategy the possibility of keeping the temperature of thecooling fluid below the maximum permissible temperature Tmax downstreamof the converter 10 is optimized even under operating conditions such asoperation at maximum power.

If such a result is not achieved, whether at high or at low speed, it isstill possible to reduce the operating load of the refrigerant-fluidcirculation loop, for example by limiting a maximum speed of thecompression device 50.

This is illustrated in the embodiment of FIG. 5, for the case of thevehicle moving at low speed, and therefore in an eleventh step 120. Thechoice is then made as to whether to prioritize good operation of thevehicle air conditioning, in a twelfth step 122, or the cooling of theelectrical storage device, in a thirteenth step 124. The circulation ofthe refrigerant fluid through the exchangers concerned is then adaptedin a fourteenth step 126, following which the monitoring continues,looping back to the first step 100.

Advantageously, said threshold vehicle speed, namely the speed below orabove which the order of steps (a), (b) and (c) varies, may be adjustedaccording to the ambient temperature.

The invention further relates to a heat exchange module, notillustrated, comprising the first, the second as well as the third heatexchanger 2, 4 and 6 and/or the fourth exchanger 16. Said module mayfurthermore advantageously comprise the three-way valve 18.

The module comprises, for example, a frame on which said first heatexchanger 2, second heat exchanger 4, third heat exchanger 6, fourthheat exchanger 16 and/or said three-way valve 18 are fixed. Said frameis configured to be fixed directly or indirectly to a chassis of thevehicle.

1. A method for controlling a circuit for the thermal regulation of avehicle, said circuit comprising a first and a second heat exchangerwhich are situated in series in a direction in which an air flowintended to pass through them in this order circulates, an additionalheat exchanger situated upstream of the first heat exchanger accordingto the direction of circulation of the air flow, said circuit beingconfigured to allow a refrigerant fluid to circulate through the firstexchanger and a heat-transfer fluid to circulate through the secondexchanger and through the additional exchanger, said method comprising:generating a flow of the heat-transfer fluid in the additional exchangeris generated or increased according to the mode of operation of thecircuit.
 2. The method as claimed in claim 1, wherein said circuit isconfigured in such a way that the air flow passing through saidadditional heat exchanger is an ambient air flow.
 3. The method asclaimed in claim 1, further comprising: controlling at least oneparameter relating to the heat-transfer fluid, said parameter being thetemperature of the heat-transfer fluid, in which method the step whereinthe flow of heat-transfer fluid in the additional exchanger is generatedor increased is performed by comparing the value of the parameteragainst a threshold value.
 4. The method as claimed in claim 1, whereinsaid circuit is configured so that the circulation of the heat-transferfluid allows a cooling of an electric converter configured to convert aDC electric current delivered by an electrical storage device into an ACcurrent for powering an electric motor capable of causing said vehicleto move.
 5. The method as claimed in claim 4, further comprising:selectively allowing a circulation of the heat-transfer fluid throughthe second exchanger and a circulation of the heat-transfer fluidthrough the second exchanger and through the additional heat exchanger.6. The method as claimed in claim 5, wherein said circuit comprises atleast one valve for directing the heat-transfer fluid downstream of thesecond exchanger selectively, according to the direction of circulationof said heat-transfer fluid, toward said additional exchanger or towardthe component or components of the electric powertrain of the vehicle.7. The method as claimed in claim 1, wherein the circulation of theheat-transfer fluid through the second heat exchanger and through theadditional heat exchanger is in series.
 8. The method as claimed inclaim 1, wherein said first and second heat exchangers as well as saidadditional exchanger are configured to be positioned on the front faceof the vehicle.
 9. The method as claimed in claim 1, wherein the coolingfluid is cooled in the following sub-steps: a sub-step (a) wherein saidair flow is generated and/or accelerated using a motor-fan unit, and/ora sub-step (b) wherein a cross section for the passage of said air flowis increased by opening one or more mobile flaps or shutters intended tolimit a flow rate of said air flow, a sub-step (c) wherein the flow ofthe heat-transfer fluid through said additional heat exchanger isgenerated and/or increased, and wherein the order of said sub-steps ismodified according to the speed of the vehicle.
 10. The method asclaimed in claim 9, wherein, when the vehicle speed is above a thresholdspeed, there is an envisioned initial situation in which the flaps orshutters are closed so that the cross section for the passage of saidair flow is nil or minimal.